In technology for connection of optical fibers, there is known an optical connector equipped with a ferrule securing supporting an optical fiber from which the coating has been removed at a predetermined position of the connector body. A single-fiber ferrule generally is a cylindrical member formed with a through hole for holding the fiber along its center axis and provided with an abutting end face at one end in the axial direction of a centering part having a cylindrical outer circumference and a fiber holding channel opening at the abutting end face and securely holding the optical fiber in the centering part (for example, see Japanese Unexamined Patent Publication (Kokai) No. 2000-235132). This type of optical connector forms a connector able to be connected to and disconnected from an optical transmission line and can be used attached to an end of an optical transmission-line member, such as an optical fiber cord or optical fiber cable, including a coated optical fiber. Note that in this specification, an “optical fiber cord” means a coated optical fiber wound around with a tension-bearing plastic fiber and formed over that with a plastic sheath which can be simply used for connection between parts in an optical device or between optical devices. Further, an “optical fiber cable” means a plurality of coated optical fibers bundled together and housed in a plastic sheath together with a wire-shaped tension-bearing member which is used for connection between telephone exchange offices or between a terminal office and subscribers.
When using an optical connector with a ferrule to interconnect a pair of coated optical fibers, an aligning sleeve member is used for coaxially positioning and holding in alignment the ferrules of the optical connectors attached to the front ends of the two coated optical fibers in a state with the abutting end faces abutting against each other. The aligning sleeve member is provided with a tubular elastic positioning element called a “slotted sleeve”. This slotted sleeve contacts the cylindrical outer circumference of the centering part of the ferrule to be connected and is elastically pushed wider so as to center and support the ferrule at a predetermined position under this elastic recovery force. Therefore, by inserting into one slotted sleeve of the aligning sleeve member the centering parts of a pair of ferrules holding optical fibers in their fiber holding channels, these centering parts are aligned coaxially in the axial direction. Further, by making the abutting end faces of the two ferrules abut by for example a spring bias force, the pair of coated optical fibers is connected in a state with the end faces abutting against each other centered to a high accuracy.
As an optical fiber connecting device using optical connectors with ferrules and an aligning sleeve member to connect coated optical fibers, there is known a configuration using a pair of optical connectors differing in shapes of connector bodies, i.e., of the so-called plug (male) type and socket (female) type. In this configuration, the body of the socket type connector is usually provided with an engagement recess for receiving the part around the ferrule of the body of the plug-type connector. Further, the aligning sleeve member is set secured or detachably in the engagement recess of the socket-type connector body in a state receiving the ferrule of the socket-type connector in advance (for example, see Japanese Unexamined Patent Publication (Kokai) No. 10-111434).
In this way, optical fiber connecting devices employing optical connectors with ferrules are configured with the pair of ferrules aligned in the axial direction inside the slotted sleeve of the aligning sleeve member, so the external dimensions of the devices in the direction of extension of the ferrule tend to become relatively large. As a result, depending on the set locations of the optical fiber connecting devices, sometimes it is necessary to lay the optical fiber cords (or optical fiber cables) extending from the individual optical connectors bent large near the optical connectors. At that time, from the viewpoint of suppressing optical loss, an optical connector provided with a guide for restricting the radius of curvature of the optical fiber cord so that the coated optical fiber is not bent by a radius smaller than the prescribed value of the minimum radius of curvature has been proposed (for example, see Japanese Unexamined Patent Publication (Kokai) No. 2003-161863).